Bonding system

ABSTRACT

A bonding system includes a first holder and a second holder arranged to be spaced apart from each other in a vertical direction; a position adjuster configured to move the first holder and the second holder relatively to perform a position adjustment in a horizontal direction between a first substrate held by the first holder and a second substrate held by the second holder; a pressing unit configured to press the first substrate and the second substrate against each other; a measuring unit configured to measure a position deviation between an alignment mark on the first substrate and an alignment mark on the second substrate, the first substrate and the second substrate being bonded by the pressing unit; and a position adjustment controller configured to control the position adjustment in the horizontal direction in a currently-performed bonding processing based on the position deviation generated in a previously-performed bonding processing.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. patent application Ser. No.16/964,070, filed on Jul. 22, 2020, which claims the benefit of JapanesePatent Application No. 2018-008892 filed on Jan. 23, 2018, the entiredisclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The various aspects and embodiments described herein pertain generallyto a bonding system and a bonding method.

BACKGROUND

A bonding apparatus described in Patent Document 1 is equipped with anupper chuck configured to attract a substrate at an upper side fromabove it and a lower chuck configured to attract a substrate at a lowerside from below it. While being held to face each other, the twosubstrates are bonded. To elaborate, the bonding apparatus brings acentral portion of the upper substrate attracted by the upper chuck intocontact with a central portion of the lower substrate attracted by thelower chuck by pressing down the central portion of the upper substrate.Accordingly, the central portions of the two substrates are bonded by anintermolecular force or the like. Then, the bonding apparatus expands abonding region between the two substrates from the central portions ofthe substrates to peripheral portions thereof.

The bonding apparatus includes an upper imaging device fixed to theupper chuck; a lower imaging device fixed to the lower chuck; and amoving device configured to move the upper chuck and the lower chuckrelatively. The upper imaging device is configured to image an alignmentmark formed on the lower substrate which is attracted to the lowerchuck. Meanwhile, the lower imaging device is configured to image analignment mark formed on the upper substrate which is attracted to theupper chuck.

The bonding apparatus measures relative horizontal positions of theupper substrate and the lower substrate based on the images obtained bythe upper imaging device and the lower imaging device. The bondingapparatus moves the upper chuck and the lower chuck relatively so thatthe alignment mark of the upper substrate and the alignment mark of thelower substrate are overlapped when viewed in the vertical direction.Then, the bonding apparatus bonds the upper substrate and the lowersubstrate.

PRIOR ART DOCUMENT

Patent Document 1: Japanese Patent Laid-open Publication No. 2015-095579

SUMMARY

In an exemplary embodiment, a bonding system includes a first holder anda second holder arranged to be spaced apart from each other in avertical direction, the first holder having, on a surface thereof facingthe second holder, an attraction surface configured to attract and holda first substrate, and the second holder having, on a surface thereoffacing the first holder, an attraction surface configured to attract andhold a second substrate; a position adjuster configured to move thefirst holder and the second holder relatively to perform a positionadjustment in a horizontal direction between the first substrate held bythe first holder and the second substrate held by the second holder; apressing unit configured to press the first substrate held by the firstholder and the second substrate held by the second holder against eachother; a measuring unit configured to measure a position deviationbetween an alignment mark formed on the first substrate and an alignmentmark formed on the second substrate, the first substrate and the secondsubstrate being bonded by the pressing unit; and a position adjustmentcontroller configured to control the position adjustment in thehorizontal direction in a currently-performed bonding processing basedon the position deviation generated in a previously-performed bondingprocessing.

According to the exemplary embodiments, it is possible to improveaccuracy of position adjustment between a substrate at an upper side anda substrate at a lower side in the horizontal direction, which isperformed before bonding of the two substrates is carried out.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a bonding system according to anexemplary embodiment.

FIG. 2 is a side view illustrating the bonding system according to theexemplary embodiment.

FIG. 3 is a side view illustrating a state before a first substrate anda second substrate are bonded according to the exemplary embodiment.

FIG. 4 is a plan view illustrating a bonding apparatus according to theexemplary embodiment.

FIG. 5 is a side view illustrating the bonding apparatus according tothe exemplary embodiment.

FIG. 6 is a cross sectional view illustrating an upper chuck and a lowerchuck according to the exemplary embodiment, showing a state before anupper wafer and a lower wafer are bonded after their positions areadjusted.

FIG. 7A and FIG. 7B are cross sectional views illustrating an operationthrough which the upper wafer and the lower wafer are gradually bondedfrom central portions toward peripheral portions thereof according tothe exemplary embodiment.

FIG. 8 is a flowchart illustrating a part of a processing performed bythe bonding system according to the exemplary embodiment.

FIG. 9A to FIG. 9C are explanatory diagrams illustrating operationsthrough which horizontal positions of the upper wafer and the lowerwafer are adjusted according to the exemplary embodiment.

FIG. 10 is a cross sectional view illustrating an alignment measuringdevice according to the exemplary embodiment.

FIG. 11 is a functional block diagram illustrating constituentcomponents of a control device according to the exemplary embodiment.

FIG. 12A and FIG. 12B are explanatory diagrams illustrating a processingperformed by a measurement data analyzer according to the exemplaryembodiment.

FIG. 13 is a flowchart illustrating a processing of deciding settings ofthe bonding apparatus based on the measurement data of the alignmentmeasuring device according to the exemplary embodiment.

FIG. 14 is a flowchart illustrating an operation of the bondingapparatus based on the measurement data of the alignment measuringdevice according to the exemplary embodiment.

FIG. 15 is a plan view illustrating an attraction surface of the lowerchuck according to the exemplary embodiment.

FIG. 16 is a side view illustrating the upper chuck, the lower chuck anda temperature distribution adjuster according to the exemplaryembodiment.

FIG. 17 is a side cross sectional view illustrating a main body of thetemperature distribution adjuster according to the exemplary embodiment.

FIG. 18A and FIG. 18B are side cross sectional views illustrating alower chuck according to a modification example.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. In thevarious drawings, same or corresponding parts will be assigned samereference numerals, and redundant description may be omitted. In thefollowing description, the X-axis direction, the Y-axis direction andthe Z-axis direction are orthogonal to each other, and the X-axis andY-axis directions are horizontal directions whereas the Z-axis directionis a vertical direction. A rotational direction around a vertical axisis also referred to as “θ direction.” In the present specification,below means vertically below, and above means vertically above.

<Bonding System>

FIG. 1 is a plan view illustrating a bonding system 1 according to anexemplary embodiment. FIG. 2 is a side view illustrating the bondingsystem 1 according to the exemplary embodiment. FIG. 3 is a side viewillustrating a state before a first substrate and a second substrate arebonded according to the exemplary embodiment. The bonding system 1 shownin FIG. 1 forms a combined substrate T (see FIG. 7B) by bonding a firstsubstrate W1 and a second substrate W2.

The first substrate W1 is, for example, a semiconductor substrate suchas a silicon wafer or a compound semiconductor wafer on which multipleelectronic circuits are formed. The second substrate W2 is, for example,a bare wafer on which no electronic circuit is formed. The firstsubstrate W1 and the second substrate W2 have the substantially samediameter. Further, the second substrate W2 may have an electroniccircuit formed thereon.

In the following description, the first substrate W1 may sometimes bereferred to as “upper wafer W1”; the second substrate W2, “lower waferW2”; and the combined substrate T, “combined wafer T.” Further, in thefollowing description, as depicted in FIG. 3 , among surfaces of theupper wafer W1, a surface to be bonded to the lower wafer W2 will bereferred to as “bonding surface W1 j”, and a surface opposite to thebonding surface W1 j will be referred to as “non-bonding surface W1 n”.Further, among surfaces of the lower wafer W2, a surface to be bonded tothe upper wafer W1 will be referred to as “bonding surface W2 j”, and asurface opposite to the bonding surface W2 j will be referred to as“non-bonding surface W2 n.”

As depicted in FIG. 1 , the bonding system 1 includes a carry-in/outstation 2 and a processing station 3. The carry-in/out station 2 and theprocessing station 3 are arranged in this sequence along the positiveX-axis direction. Further, the carry-in/out station 2 and the processingstation 3 are connected as a single body.

The carry-in/out station 2 includes a placing table 10 and a transfersection 20. The placing table 10 is equipped with a multiple number ofplacing plates 11. Provided on the placing plates 11 are cassettes C1,C2 and C3 each of which accommodates therein a plurality of (e.g., 25sheets of) substrates horizontally. For example, the cassette C1accommodates therein upper wafers W1; the cassette C2, lower wafers W2;and the cassettes C3, combined wafers T.

The transfer section 20 is provided adjacent to the positive X-axis sideof the placing table 10. Provided in the transfer section 20 are atransfer path 21 extending in the Y-axis direction and a transfer device22 configured to be movable along the transfer path 21. The transferdevice 22 is configured to be movable in the X-axis direction as well asin the Y-axis direction and pivotable around the Z-axis. Further, thetransfer device 22 is also configured to transfer the upper wafers W1,the lower wafers W2 and the combined wafers T between the cassettes C1to C3 placed on the placing plates 11 and a third processing block G3and the fourth processing block G4 of the processing station 3 to bedescribed later.

Further, the number of the cassettes C1 to C3 placed on the placingplates 11 is not limited to the shown example. In addition, besides thecassettes C1 to C3, a cassette for collecting a problematic substrate orthe like may be additionally provided on the placing plates 11.

A multiple number of, for example, four processing blocks G1, G2, G3 andG4 equipped with various kinds of devices are provided in the processingstation 3. For example, the first processing block G1 is provided at afront side (negative Y-axis side of FIG. 1 ) of the processing station3, and the second processing block G2 is provided at a rear side(positive Y-axis side of FIG. 1 ) of the processing station 3. Further,the third processing block G3 is provided at a side of the carry-in/outstation 2 (negative X-axis side of FIG. 1 ) of the processing station 3.In the processing station 3, the fourth processing block G4 is providedat a side opposite to the carry-in/out station 2 (positive X-axis sideof FIG. 1 ).

Provided in the first processing block G1 is a surface modifyingapparatus 30 configured to modify the bonding surface W1 j of the upperwafer W1 and the bonding surface W2 j of the lower wafer W2. In thesurface modifying apparatus 30, a SiO₂ bond on the bonding surfaces W1 jand W2 j of the upper wafer W1 and the lower wafer W2 is cut to beturned into SiO of a single bond, so that the bonding surfaces W1 j andW2 j are modified such that these surfaces are easily hydrophilizedafterwards.

Furthermore, in the surface modifying apparatus 30, for example, anoxygen gas or a nitrogen gas as a processing gas is excited into plasmaunder a decompressed atmosphere to be ionized. As these oxygen ions ornitrogen ions are irradiated to the bonding surfaces W1 j and W2 j ofthe upper wafer W1 and the lower wafer W2, the bonding surfaces W1 j andW2 j are plasma-processed to be modified.

In the second processing block G2, a surface hydrophilizing apparatus 40and a bonding apparatus 41 are disposed. The surface hydrophilizingapparatus 40 is configured to hydrophilize and clean the bondingsurfaces W1 j and W2 j of the upper wafer W1 and the lower wafer W2with, for example, pure water. In this surface hydrophilizing apparatus40, while rotating the upper wafer W1 or the lower wafer W2 held by, forexample, a spin chuck, the pure water is supplied onto the upper waferW1 or the lower wafer W2. Accordingly, the pure water supplied onto theupper wafer W1 or the lower wafer W2 is diffused onto the bondingsurface W1 j of the upper wafer W1 or the bonding surface W2 j of thelower wafer W2, so that the bonding surfaces W1 j and W2 j arehydrophilized.

The bonding apparatus 41 is configured to bond the upper wafer W1 andthe lower wafer W2, which are hydrophilized, by an intermolecular force.A configuration of the bonding apparatus 41 will be discussed later.

In the third processing block G3, as shown in FIG. 2 , transition (TRS)devices 50 and 51 for the upper wafer W1, the lower wafer W2 and thecombined wafer T are provided in two levels in this order from below.

Provided in the fourth processing block G4 is an alignment measuringdevice 55. The alignment measuring device 55 is configured to measure arelative position deviation between the upper wafer W1 and the lowerwafer W2 bonded by the bonding apparatus 41. The alignment measuringdevice 55 outputs measurement data to a control device 70 to bedescribed later.

Further, the alignment measuring device 55 may be disposed at an outsideof the processing station 3 as long as it is capable of transmitting themeasurement data to the control device 70. By way of example, thecombined wafer T may be carried out to the outside of the processingstation 3 through the carry-in/out station 2 from the processing station3, and then subjected to the measurement by the alignment measuringdevice 55.

Further, as illustrated in FIG. 1 , a transfer section 60 is formed in aregion surrounded by the first processing block G1, the secondprocessing block G2, the third processing block G3 and the fourthprocessing block G4. A transfer device 61 is provided in the transfersection 60. The transfer device 61 is equipped with, for example, atransfer arm which is configured to be movable in a vertical directionand a horizontal direction and pivotable around a vertical axis. Thetransfer device 61 is moved within the transfer section 60 and transfersthe upper wafers W1, the lower wafers W2 and the combined wafers T withrespect to preset devices within the first processing block G1, thesecond processing block G2, the third processing block G3 and the fourthprocessing block G4 which are adjacent to the transfer section 60.

Furthermore, as depicted in FIG. 1 , the bonding system 1 includes acontrol device 70. The control device 70 controls an operation of thebonding system 1. The control device 70 may be implemented by, forexample, a computer and includes, as illustrated in FIG. 1 , a CPU(Central Processing Unit) 71, a recording medium 72 such as a memory, aninput interface 73 and an output interface 74. The control device 70carries out various kinds of controls by allowing the CPU 71 to executea program stored in the recording medium 72. Further, the control device70 receives a signal from an outside through the input interface 73 andtransmits a signal to the outside through the output interface 74.

The program of the control device 70 is recorded in an informationrecording medium and installed from the information recording medium.The information recording medium may be, by way of non-limiting example,a hard disc (HD), a flexible disc (FD), a compact disc (CD), a magnetoptical disc (MO), or a memory card. Further, the program may beinstalled by being downloaded from a server through Internet.

<Bonding Apparatus>

FIG. 4 is a plan view illustrating the bonding apparatus 41 according tothe exemplary embodiment. FIG. 5 is a side view illustrating the bondingapparatus 41 according to the exemplary embodiment.

As depicted in FIG. 4 , the bonding apparatus 41 includes a processingvessel 100 having a hermetically sealable inside. A carry-in/out opening101 for the upper wafer W1, the lower wafer W2 and the combined wafer Tis formed on a lateral side of the processing vessel 100 at a side ofthe transfer section 60. A shutter 102 for opening/closing thecarry-in/out opening 101 is provided at the carry-in/out opening 101.

The inside of the processing vessel 100 is partitioned into a transferregion T1 and a processing region T2 by an inner wall 103. Theaforementioned carry-in/out opening 101 is formed at a side surface ofthe processing vessel 100 in the transfer region T1. Further, acarry-in/out opening 104 for the upper wafer W1, the lower wafer W2 andthe combined wafer T is formed at the inner wall 103.

In the transfer region T1, a transition 110, a wafer transfer device111, an inverting device 130 and a position adjusting device 120 arearranged side by side in this sequence from, for example, a carry-in/outopening 101 side.

The transition 110 is configured to temporarily place thereon the upperwafer W1, the lower wafer W2 and the combined wafer T. The transition110 has, for example, two levels, and is capable of holding any two ofthe upper wafer W1, the lower wafer W2 and the combined wafer T.

The wafer transfer device 111 is equipped with a transfer arm configuredto be movable in the vertical direction (Z-axis direction) and thehorizontal directions (Y-axis direction and X-axis direction) and alsopivotable around a vertical axis, as shown in FIG. 4 and FIG. 5 . Thewafer transfer device 111 is capable of transferring the upper wafer W1,the lower wafer W2 and the combined wafer T within the transfer regionT1 or between the transfer region T1 and the processing region T2.

The position adjusting device 120 is configured to adjust a direction ofthe upper wafer W1 (lower wafer W2) in the horizontal direction. Toelaborate, the position adjusting device 120 includes a base 121equipped with a non-illustrated holder configured to hold and rotate theupper wafer W1 (lower wafer W2); and a detector 122 configured to detecta position of a notch of the upper wafer W1 (lower wafer W2). Theposition adjusting device 120 adjusts the position of the notch of theupper wafer W1 (lower wafer W2) by detecting the position of the notchwith the detector 122 while rotating the upper wafer W1 (lower wafer W2)held by the base 121. Accordingly, the position of the upper wafer W1(lower wafer W2) in the horizontal direction is adjusted.

The inverting device 130 is configured to invert a front surface and arear surface of the upper wafer W1. To elaborate, the inverting device130 is equipped with a holding arm 131 configured to hold the upperwafer W1. The holding arm 131 extends in the horizontal direction(X-axis direction). Further, the holding arm 131 is provided with, atfour positions, for example, holding members 132 configured to hold theupper wafer W1.

The holding arm 131 is supported by a driving unit 133 having, forexample, a motor or the like. The holding arm 131 is configured to berotatable around a horizontal axis by the driving unit 133. Further, theholding arm 131 is rotatable around the driving unit 133 and movable inthe horizontal direction (X-axis direction). Another driving unit (notshown) including, for example, a motor or the like is provided under thedriving unit 133. The driving unit 133 can be moved in the verticaldirection along a vertically extending supporting column 134 by thisanother driving unit.

Further, the upper wafer W1 held by the holding members 132 can berotated around the horizontal axis by the driving unit 133 and can alsobe moved in the vertical direction and the horizontal direction.Further, the upper wafer W1 held by the holding members 132 can be movedbetween the position adjusting device 120 and an upper chuck 140 to bedescribed later by being rotated around the driving unit 133.

Provided within the processing region T2 are the upper chuck 140configured to attract and hold a top surface (non-bonding surface W1 n)of the upper wafer W1 from above and a lower chuck 141 configured toplace thereon the lower wafer W and attract and hold a bottom surface(non-bonding surface W2 n) of the lower wafer W2 from below. The lowerchuck 141 is provided under the upper chuck 140 and configured to bearranged to face the upper chuck 140 in parallel. The upper chuck 140and the lower chuck 141 are arranged apart from each other in thevertical direction.

As depicted in FIG. 5 , the upper chuck 140 is held by an upper chuckholder 150 which is provided above the upper chuck 140. The upper chuckholder 150 is provided at a ceiling surface of the processing vessel100. The upper chuck 140 is fixed to the processing vessel 100 with theupper chuck holder 150 therebetween.

The upper chuck holder 150 is equipped with an upper imaging device 151configured to image a top surface (bonding surface W2 j) of the lowerwafer W2 held by the lower chuck 141. By way of example, a CCD camera isused as the upper imaging device 151.

The lower chuck 141 is supported by a first lower chuck mover 160provided below the lower chuck 141. The first lower chuck mover 160moves the lower chuck 141 in the horizontal direction (X-axis direction)as will be described later. Further, the first lower chuck mover 160 isalso configured to be capable of moving the lower chuck 141 in thevertical direction and rotate the lower chuck 141 around a verticalaxis.

The first lower chuck mover 160 is equipped with a lower imaging device161 configured to image a bottom surface (bonding surface W1 j) of theupper wafer W1 held by the upper chuck 140 (see FIG. 5 ). The lowerimaging device 161 may be, by way of example, a CCD camera.

The first lower chuck mover 160 is fastened to a pair of rails 162 whichis provided at a bottom side of the first lower chuck mover 160 andextends in the horizontal direction (X-axis direction). The first lowerchuck mover 160 is configured to be movable along the rails 162.

The rails 162 are disposed on a second lower chuck mover 163. The secondlower chuck mover 163 is fastened to a pair of rails 164 which isdisposed at a bottom side of the second lower chuck mover 163 andextends in the horizontal direction (Y-axis direction). The second lowerchuck mover 163 is configured to be movable in the horizontal direction(Y-axis direction) along the rails 164. Further, the rails 164 isdisposed on the placing table 165 which is disposed at a bottom of theprocessing vessel 100.

The first lower chuck mover 160, the second lower chuck mover 163, andso forth constitute a position adjuster 166. The position adjuster 166is configured to perform position adjustment in the horizontal directionbetween the upper wafer W1 held by the upper chuck 140 and the lowerwafer W2 held by the lower chuck 141 by moving the lower chuck 141 inthe X-axis direction, the Y-axis direction and the 0 direction. Further,the position adjuster 166 is also configured to perform positionadjustment in the vertical direction between the upper wafer W1 held bythe upper chuck 140 and the lower wafer W2 held by the lower chuck 141by moving the lower chuck 141 in the Z-axis direction.

Further, although the position adjuster 166 of the present exemplaryembodiment carries out the position adjustment between the upper waferW1 and the lower wafer W2 in the horizontal direction by moving thelower chuck 141 in the X-axis direction, the Y-axis direction and the 0direction, the present disclosure is not limited thereto. The way howthe position adjuster 166 performs this position adjustment in thehorizontal direction is not particularly limited as long as the upperchuck 140 and the lower chuck 141 are moved relatively to each other inthe X-axis direction, the Y-axis direction and the 0 direction. By wayof example, the position adjuster 166 may perform the positionadjustment in the horizontal direction between the upper wafer W1 andthe lower wafer W2 by moving the lower chuck 141 in the X-axis directionand the Y-axis direction and by moving the upper chuck 140 in the 0direction.

Furthermore, although the position adjuster 166 of the presentdisclosure carries out the position adjustment between the upper waferW1 and the lower wafer W2 in the vertical direction by moving the lowerchuck 141 in the Z-axis direction, the present disclosure is not limitedthereto. The way how the position adjuster 166 performs this positionadjustment in the vertical direction is not particularly limited as longas the upper chuck 140 and the lower chuck 141 can be moved relativelyto each other in the Z-axis direction. By way of example, the positionadjuster 166 may perform the position adjustment between the upper waferW1 and the lower wafer W2 in the vertical direction by moving the upperchuck 140 in the Z-axis direction.

FIG. 6 is a cross sectional view illustrating the upper chuck and thelower chuck according to the exemplary embodiment, showing a stateimmediately before the upper wafer and the lower wafer are bonded. FIG.7A is a cross sectional view illustrating a state in the middle ofbonding between the upper wafer and the lower wafer according to thepresent exemplary embodiment. FIG. 7B is a cross sectional viewillustrating a state upon the completion of the bonding between theupper wafer and the lower wafer according to the present exemplaryembodiment. Solid-lined arrows in FIG. 6 , FIG. 7A and FIG. 7B indicatea direction in which air is suctioned by a vacuum pump.

The upper chuck 140 and the lower chuck 141 are, for example, vacuumchucks. In the present exemplary embodiment, the upper chuck 140corresponds to a first holder described in claims, and the lower chuck141 corresponds to a second holder described in the claims. The upperchuck 140 has, at the surface (bottom surface) thereof facing the lowerchuck 141, an attraction surface 140 a to which the upper wafer W1 isattracted. Meanwhile, the lower chuck 141 has, at the surface (topsurface) facing the upper chuck 140, an attraction surface 141 a towhich the lower wafer W2 is attracted.

The upper chuck 140 has a chuck base 170. The chuck base 170 has adiameter equal to or larger than a diameter of the upper wafer W1. Thechuck base 170 is supported by a supporting member 180. The supportingmember 180 is disposed to cover at least the chuck base 170 when viewedfrom the top, and is fixed to the chuck base 170 by, for example,screws. The supporting member 180 is supported by a plurality ofsupporting columns 181 (see FIG. 5 ) provided at the ceiling surface ofthe processing vessel 100. The supporting member 180 and the pluralityof supporting columns 181 constitute the upper chuck holder 150.

A through hole 176 is formed through the supporting member 180 and thechuck base 170 in the vertical direction. A position of the through hole176 corresponds to a central portion of the upper wafer W1 attracted toand held by the upper chuck 140. A push pin 191 of a striker 190 isinserted into this through hole 176.

The striker 190 is provided on a top surface of the supporting member180 and is equipped with the push pin 191, an actuator unit 192 and alinearly moving mechanism 193. The push pin 191 is a columnar memberextending along the vertical direction and is supported by an actuatorunit 192.

The actuator unit 192 is configured to generate a constant pressure in acertain direction (here, a vertically downward direction) by airsupplied from, for example, an electro-pneumatic regulator (not shown).By the air supplied from the electro-pneumatic regulator, the actuatorunit 192 is capable of controlling a press load applied to the centralportion of the upper wafer W1 as it is brought into contact with thecentral portion of the upper wafer W1. Further, a leading end of thepush pin 191 is movable up and down in the vertical direction throughthe through hole 176 by the air from the electro-pneumatic regulator.

The actuator unit 192 is supported at the linearly moving mechanism 193.The linearly moving mechanism 193 moves the actuator unit 192 in thevertical direction by a driving unit including a motor, for example.

The striker 190 is configured as described above, and controls amovement of the actuator unit 192 by the linearly moving mechanism 193and controls the press load upon the upper wafer W1 from the push pin191 by the actuator unit 192.

The striker 190 presses the upper wafer W1 attracted to and held by theupper chuck 140 and the lower wafer W2 attracted to and held by thelower chuck 141 to allow the upper wafer W1 and the lower wafer W2 tocome into contact with each other. To elaborate, the striker 190transforms the upper wafer W1 attracted to and held by the upper chuck140, thus allowing the upper wafer W1 to be pressed in contact with thelower wafer W2. The striker 190 corresponds to a pressing unit describedin the claims.

A plurality of pins 171 is provided on a bottom surface of the chuckbase 170, and these pins 171 are in contact with the non-bonding surfaceWin of the upper wafer W1. The upper chuck 140 is composed of the chuckbase 170, the plurality of pins 171, and so forth. The attractionsurface 140 a of the upper chuck 140 which attracts and holds the upperwafer W1 is divided into multiple regions in a diametrical direction,and generation of an attracting pressure and release of the attractingpressure are performed for divided regions individually.

Further, the lower chuck 141 may be configured the same as the upperchuck 140. The lower chuck 141 has a plurality of pins in contact withthe non-bonding surface W2 n of the lower wafer W2. The attractionsurface 141 a of the lower chuck 141 which attracts and holds the lowerwafer W2 is divided into multiple regions in the diametrical direction,and generation of an attracting pressure and release of the attractingpressure are performed for divided regions individually.

<Bonding Method>

FIG. 8 is a flowchart illustrating a part of a processing performed bythe bonding system according to the exemplary embodiment. Further, thevarious processes shown in FIG. 8 are performed under the control of thecontrol device 70.

First, a cassette C1 accommodating a plurality of upper wafers W1, acassette C2 accommodating a plurality of lower wafers W2 and an emptycassette C3 are placed on the preset placing plates 11 of thecarry-in/out station 2. Then, an upper wafer W1 is taken out of thecassette C1 by the transfer device 22 and is transferred to thetransition device 50 of the third processing block G3 of the processingstation 3.

Subsequently, the upper wafer W1 is transferred into the surfacemodifying apparatus 30 of the first processing block G1 by the transferdevice 61. In the surface modifying apparatus 30, an oxygen gas as theprocessing gas is formed into plasma to be ionized under the presetdecompressed atmosphere. The oxygen ions are irradiated to the bondingsurface W1 j of the upper wafer W1, and the bonding surface W1 j isplasma-processed. As a result, the bonding surface W1 j of the upperwafer W1 is modified (process S101).

Then, the upper wafer W1 is transferred into the surface hydrophilizingapparatus 40 of the second processing block G2 by the transfer device61. In the surface hydrophilizing apparatus 40, the pure water issupplied onto the upper wafer W1 while rotating the upper wafer W1 heldby the spin chuck. The supplied pure water is diffused on the bondingsurface W1 j of the upper wafer W1, and hydroxyl groups (silanol groups)adhere to the bonding surface W1 j of the upper wafer W1 modified in thesurface modifying apparatus 30, so that the bonding surface W1 j ishydrophilized (process S102). Further, the bonding surface W1 j of theupper wafer W1 is cleaned by this pure water used to hydrophilize thebonding surface W1 j.

Thereafter, the upper wafer W1 is transferred into the bonding apparatus41 of the second processing block G2 by the transfer device 61. Theupper wafer W1 transferred into the bonding apparatus 41 is thendelivered into the position adjusting mechanism 120 via the transition110 by the wafer transfer mechanism 111. Then, the direction of theupper wafer W1 in the horizontal direction is adjusted by the positionadjusting mechanism 120 (process S103).

Subsequently, the upper wafer W1 is delivered from the positionadjusting mechanism 120 onto the holding arm 131 of the invertingmechanism 130. Then, in the transfer region T1, by inverting the holdingarm 131, the front surface and the rear surface of the upper wafer W1are inverted (process S104). That is, the bonding surface Wij of theupper wafer W1 is turned to face down.

Afterwards, the holding arm 131 of the inverting mechanism 130 isrotated to be located under the upper chuck 140. Then, the upper waferW1 is delivered to the upper chuck 140 from the inverting mechanism 130.The non-bonding surface Win of the upper wafer W1 is attracted to andheld by the upper chuck 140 in the state that the notch of the upperwafer W1 is oriented to a predetermined direction (process S105).

While the above-described processes S101 to S105 are being performed onthe upper wafer W1, a processing of the lower wafer W2 is performed.First, the lower wafer W2 is taken out of the cassette C2 by thetransfer device 22 and transferred into the transition device 50 of theprocessing station 3 by the transfer device 22.

Thereafter, the lower wafer W2 is transferred into the surface modifyingapparatus 30 by the transfer device 61, and the bonding surface W2 j ofthe lower wafer W2 is modified (process S106). Further, the modificationof the bonding surface W2 j of the lower wafer W2 in the process S106 isthe same as the above-stated process S101.

Then, the lower wafer W2 is transferred into the surface hydrophilizingapparatus 40 by the transfer device 61, and the bonding surface W2 j ofthe lower wafer W2 is hydrophilized (process S107). Further, the bondingsurface W2 j is cleaned by the pure water used to hydrophilize thebonding surface W2 j. The hydrophilizing of the bonding surface W2 j ofthe lower wafer W2 in the process S107 is the same as the hydrophilizingof the bonding surface W1 j of the upper wafer W1 in the above-describedprocess S102.

Thereafter, the lower wafer W2 is transferred into the bonding apparatus41 by the transfer device 61. The lower wafer W2 transferred into thebonding apparatus 41 is then sent into the position adjusting mechanism120 via the transition 110 by the wafer transfer mechanism 111. Then,the direction of the lower wafer W2 in the horizontal direction isadjusted by the position adjusting mechanism 120 (process S108).

Afterwards, the lower wafer W2 is transferred onto the lower chuck 141by the wafer transfer mechanism 111 and attracted to and held by thelower chuck 141 (process S109). At this time, the non-bonding surface W2n of the lower wafer W2 is attracted to and held by the lower chuck 141in the state that the notch of the lower wafer W2 is oriented to thesame direction as the notch of the upper wafer W1.

Thereafter, the position adjustment in the horizontal direction betweenthe upper wafer W1 held by the upper chuck 140 and the lower wafer W2held by the lower chuck 141 is performed (process S110). In thisposition adjustment, the alignment marks W1 a, W1 b and W1 c (see FIG.9A to FIG. 9C) previously formed on the bonding surface W1 j of theupper wafer W1 and the alignment marks W2 a, W2 b and W2 c previouslyformed on the bonding surface W2 j of the lower wafer W2 (see FIG. 9A toFIG. 9C) are used.

An operation of the position adjustment of the upper wafer W1 and thelower wafer W2 in the horizontal direction will be elaborated withreference to FIG. 9A to FIG. 9C. FIG. 9A is a diagram for describing anoperation of performing the position adjustment between the upperimaging device and the lower imaging device according to the presentexemplary embodiment. FIG. 9B is a diagram for describing an imagingoperation through which the upper imaging device images the lower waferand an imaging operation through which the lower imaging device imagesthe upper wafer according to the present exemplary embodiment. FIG. 9Cis a diagram for describing an operation of performing the positionadjustment between the upper wafer and the lower wafer according to thepresent exemplary embodiment.

First, as shown in FIG. 9A, the position adjustment between the upperimaging device 151 and the lower imaging device 161 in the horizontaldirection is performed. To elaborate, the lower chuck 141 is moved inthe horizontal direction by the position adjuster 166 to allow the lowerimaging device 161 to be located under the upper imaging device 151approximately. Then, a common target 149 is checked by the upper imagingdevice 151 and the lower imaging device 161, and a position of the lowerimaging device 161 in the horizontal direction is finely adjusted sothat the positions of the upper imaging device 151 and the lower imagingdevice 161 in the horizontal direction are coincident.

Then, as depicted in FIG. 9B, the lower chuck 141 is moved in thevertically upward direction by the position adjuster 166. Then, whilemoving the lower chuck 141 in the horizontal direction by the positionadjuster 166, the alignment marks W2 c, W2 b and W2 a on the bondingsurface W2 j of the lower wafer W2 are imaged in sequence by using theupper imaging device 151. Concurrently, while moving the lower chuck 141in the horizontal direction, the alignment marks W1 a, W1 b and W1 c onthe bonding surface W1 j of the upper wafer W1 are imaged in sequence byusing the lower imaging device 161. FIG. 9B shows a state in which thealignment marks W2 c of the lower wafer W2 is imaged by the upperimaging device 151 and the alignment mark W1 a of the upper wafer W1 isimaged by the lower imaging device 161.

The obtained image data are output to the control device 70. Based onthe image data obtained by the upper imaging device 151 and the imagedata obtained by the lower imaging device 161, the control device 70controls the position adjuster 166 to adjust the position of the lowerchuck 141 in the horizontal direction. This horizontal positionadjustment is carried out such that the alignment marks W1 a, W1 b andW1 c of the upper wafer W1 and the alignment marks W2 a, W2 b and W2 cof the lower wafer W2 are respectively overlapped, when viewed in thevertical direction. In this way, the horizontal positions of the upperchuck 140 and the lower chuck 141 are adjusted, and the horizontalpositions (for example, including positions in the X-axis direction, theY-axis direction and the 0 direction) of the upper wafer W1 and thelower wafer W2 are adjusted.

Thereafter, as indicated by solid lines in FIG. 9C, the positionadjustment in the vertical direction between the upper wafer W1 held bythe upper chuck 140 and the lower wafer W2 held by the lower chuck 141is performed (process S111). To elaborate, the position adjuster 166moves the lower chuck 141 in the vertically upward direction, thusallowing the lower wafer W2 to approach the upper wafer W1. Accordingly,as shown in FIG. 6 , a distance S between the bonding surface W2 j ofthe lower wafer W2 and the bonding surface W1 j of the upper wafer W1 isadjusted to, e.g., 50 μm to 200 μm.

Subsequently, after releasing the attracting and holding of the centralportion of the upper wafer W1 by the upper chuck 140 (process S112), thepush pin 191 of the striker 190 is lowered, so that the central portionof the upper wafer W1 is pressed down (process S113), as shown in FIG.7A. If the central portion of the upper wafer W1 comes into contact withthe central portion of the lower wafer W2 and the central portion of theupper wafer W1 and the central portion of the lower wafer W2 are pressedagainst each other with a preset force, the central portion of the upperwafer W1 and the central portion of the lower wafer W2 which are pressedagainst each other are begun to be bonded. Then, a bonding wave wherebythe upper wafer W1 and the lower wafer W2 are gradually bonded from thecentral portions toward the peripheral portions thereof is generated.

Here, since the bonding surface W1 j of the upper wafer W1 and thebonding surface W2 j of the lower wafer W2 are modified in the processesS101 and S106, respectively, a Van der Waals force (intermolecularforce) is generated between the bonding surfaces W1 j and W2 j, so thatthe bonding surfaces W1 j and W2 j are bonded. Further, since thebonding surface W1 j of the upper wafer W1 and the bonding surface W2 jof the lower wafer W2 are hydrophilized in the processes S102 and S107,respectively, hydrophilic groups between the bonding surfaces W1 j andW2 j are hydrogen-bonded, so that the bonding surfaces W1 j and W2 j arefirmly bonded.

Thereafter, while pressing the central portion of the upper wafer W1 andthe central portion of the lower wafer W2 with the push pin 191, theattracting and holding of the entire upper wafer W1 by the upper chuck140 is released (process S114). Accordingly, as depicted in FIG. 7B, theentire bonding surface W1 j of the upper wafer W1 and the entire bondingsurface W2 j of the lower wafer W2 come into contact with each other,and the upper wafer W1 and the lower wafer W2 are bonded. Thereafter,the push pin 191 is raised up to the upper chuck 140, and the attractingand holding of the lower wafer W2 by the lower chuck 141 is released.

Subsequently, the combined wafer T is transferred to the alignmentmeasuring device 55 in the fourth processing block G4 by the transferdevice 61. In the alignment measuring device 55, a relative positiondeviation between the alignment marks W1 a, W1 b and W1 c formed on theupper wafer W1 and the alignment marks W2 a, W2 b and W2 c formed on thelower wafer W2 are measured (process S115).

Thereafter, the combined wafer T is transferred to the transition device51 of the third processing block G3 by the transfer device 61, and thenis transferred into the cassette C3 by the transfer device 22 of thecarry-in/out station 2. Through these processes, the series ofoperations of the bonding processing are completed.

<Alignment Measurement and Use of Measurement Data>

FIG. 10 is a cross sectional view illustrating the alignment measuringdevice according to the exemplary embodiment. The alignment measuringdevice 55 is configured to measure the relative position deviation(hereinafter, simply referred to as “position deviation”) between thealignment marks W1 a, W1 b and W1 c (see FIG. 9A to FIG. 9C) formed onthe upper wafer W1 and the alignment marks W2 a, W2 b and W2 c (see FIG.9A to FIG. 9C) formed on the lower wafer W2. In the presentspecification, the position deviation implies a position deviation whenviewed in the vertical direction with respect to the bonding surfaces W1j and W2 j of the upper wafer W1 and the lower wafer W2. The alignmentmeasuring device 55 corresponds to a measuring unit described in theclaims.

The alignment measuring device 55 is equipped with, for example, acombined wafer holder 901 configured to hold the combined wafer Thorizontally; an infrared imaging unit 902 configured to acquire aninfrared image of the combined wafer T held by the combined wafer holder901; and an infrared irradiating unit 903 configured to irradiateinfrared ray to a region of the combined wafer T from which the infraredimage is obtained.

The infrared imaging unit 902 and the infrared irradiating unit 903 areprovided at the opposite sides with the combined wafer holder 901therebetween. By way of example, the infrared imaging unit 902 isdisposed above the combined wafer holder 901, and the infraredirradiating unit 903 is disposed under the combined wafer holder 901.

The infrared imaging unit 902 and the infrared irradiating unit 903 arearranged on the same axis. The infrared ray output from the infraredirradiating unit 903 passes through an opening of the combined waferholder 901 having a ring shape to be vertically incident upon thecombined wafer T held by the combined wafer holder 901. The infrared raywhich has penetrated the combined wafer T is received by the infraredimaging unit 902.

Each infrared image obtained by the infrared imaging unit 902 includesat least one alignment mark of the upper wafer W1 and at least onealignment mark of the lower wafer W2. Therefore, the relative positiondeviation between the alignment mark of the upper wafer W1 and thealignment mark of the lower wafer W2 can be measured on each infraredimage.

The alignment measuring device 55 is further equipped with a mover (notshown) configured to move the combined wafer holder 901 in the X-axisdirection, the Y-axis direction and the 0 direction. By moving thecombined wafer holder 901, the region of the combined wafer T from whichthe infrared image is obtained can be changed, so that the positiondeviation can be measured at multiple positions of the combined wafer T.

Further, though the mover moves the combined wafer holder 901 in thepresent exemplary embodiment, the mover only needs to move the combinedwafer holder 901 and the infrared imaging unit 902 relatively. Whetherthe combined wafer holder 901 is moved or the infrared imaging unit 902is moved, the region of the combined wafer T from which the infraredimage is obtained can be changed, so that the position deviation can bemeasured at the multiple positions of the combined wafer T.

FIG. 11 is a functional block diagram illustrating constituentcomponents of the control device according to the exemplary embodiment.Individual functional blocks shown in FIG. 11 are conceptual and may notnecessarily be physically configured exactly the same as shown in FIG.11 . All or a part of the functional blocks may be functionally orphysically dispersed or combined on a unit. All or a part of processingfunctions performed in the respective functional blocks may beimplemented by a program executed by the CPU or implemented by hardwarethrough a wired logic.

As depicted in FIG. 11 , the control device 70 includes a measurementdata analyzer 701, a position adjustment controller 702, a distortioncontroller 703, and a determination unit 704. The measurement dataanalyzer 701 is configured to analyze the measurement data obtained bythe alignment measuring device 55. The position adjustment controller702 is configured to control a position adjustment within a horizontalplane between the upper wafer W1 held by the upper chuck 140 and thelower wafer W2 held by the lower chuck 141 in the currently performedbonding processing based on a position deviation generated in thepreviously performed bonding processing. The distortion controller 703is configured to control a distortion of the lower wafer W2 held by thelower chuck 141 in the currently performed bonding processing based onthe position deviation generated in the previously performed bondingprocessing. The determination unit 704 is configured to determine,through a statistical analysis, whether there is a meaningful differencebetween the position deviation generated in the previously performedbonding processing and the position deviation generated in the currentlyperformed bonding processing. If a statistical value falls out of apreset range, the determination unit 704 makes a determination thatthere is a meaningful difference. If the statistical value falls withinthe preset range, the determination unit 704 makes a determination thatthere is no meaningful difference.

FIG. 12A and FIG. 12B are explanatory diagrams illustrating a processingperformed by the measurement data analyzer according to the exemplaryembodiment. FIG. 12A is a diagram illustrating the position deviation atmultiple positions on an xy coordinate system fixed on the combinedwafer according to the exemplary embodiment. In FIG. 12A, the x-axis andthe y-axis are orthogonal to each other and parallel to the bondingsurface W1 j of the upper wafer W1 and the bonding surface W2 j of thelower wafer W2. In FIG. 12A, the x-axis fixed to the upper wafer W1 andthe x-axis fixed to the lower wafer W2 are overlapped, and the y-axisfixed to the upper wafer W1 and the y-axis fixed to the lower wafer W2are overlapped. FIG. 12B is an explanatory diagram illustrating theposition deviation at each position after parallel translation androtation are performed to minimize a size and a non-uniformity of theposition deviation shown in FIG. 12A. The x-axis and the y-axisindicated by solid lines in FIG. 12B are ones fixed to the upper waferW1, and the x-axis and the y-axis indicated by dashed lines are onesfixed to the lower wafer W2.

First, the measurement data analyzer 701 first calculates the positiondeviations at the multiple positions on the xy coordinate system fixedto the combined wafer T, as shown in FIG. 12A. In this calculation, therelative position deviations between the alignment marks W1 a, W1 b andW1 c of the upper wafer W1 and the alignment marks W2 a, W2 b and W2 cof the lower wafer W2 on the images obtained by the infrared imagingunit 902 and horizontal positions (an X-axis position, a Y-axis positionand a θ-directional position) of the combined wafer holder 901 withrespect to the infrared imaging unit 902 at the moment when the imagesare obtained are used.

Further, the number of the positions where the position deviation aremeasured is not limited to three but may be more than three.Furthermore, the shape of each alignment mark for measuring the positiondeviation is not limited to a cross-shape.

Then, the measurement data analyzer 701 calculates parallel translationsΔx and Δy and a rotation Δθ of the lower wafer W2 with respect to theupper wafer W1 to minimize the size and the non-uniformity of theposition deviation therebetween, as depicted in FIG. 12B. The paralleltranslations and the rotation are performed so that a maximum value ofthe position deviation is reduced or a standard deviation of theposition deviation is minimized, for example. Further, thenon-uniformity may be represented by a difference between the maximumvalue and the minimum value of the position deviations instead of thestandard deviation.

At this time, the measurement data analyzer 701 calculates a positiondeviation at each position after the parallel translations and therotation are performed. The calculation of the optimal paralleltranslation/rotation and the calculation of the position deviation ateach position after the optimal parallel translation/rotation areperformed are carried out substantially at the same time.

Further, though the lower wafer W2 is parallel-translated and rotated inthe present exemplary embodiment, the lower wafer W2 may beparallel-translated, and the upper wafer W1 may be rotated.Alternatively, the upper wafer W1 may be parallel-translated androtated.

FIG. 13 is a flowchart illustrating a processing of deciding settings ofthe bonding apparatus based on the measurement data of the alignmentmeasuring device according to the exemplary embodiment. Processes aftera process S201 of FIG. 13 are performed under the control of the controldevice 70 and carried out in response to, for example, a correctioninstruction for the position adjustment. The correction instruction forthe position adjustment is created when a production condition(including a production lot) of the upper wafer W1 or the lower wafer W2is changed, for example.

First, the bonding system 1 bonds the upper wafer W1 and the lower waferW2 by performing the processes S101 to S114 of FIG. 8 (process S201).Then, the alignment measuring device 55 measures the relative positiondeviation between the upper wafer W1 and the lower wafer W2 at each ofthe multiple positions, the same as in the process S115 of FIG. 8(process S202).

Thereafter, the measurement data analyzer 701 calculates the paralleltranslations Δx and Δy and the rotation Δθ to minimize thenon-uniformity and the size of the position deviation (process S203).Further, the measurement data analyzer 701 calculates the positiondeviation at each position after the parallel translations and rotationcalculated in the process S203 are performed (process S204).

Further, the calculation of the parallel translations and the rotation(process S203) and the calculation of the position deviation at eachposition after the parallel translations and the rotation are performed(process S204) are carried out substantially at the same time.

Afterwards, the measurement data analyzer 701 checks whether thecumulative number of the calculation data is equal to or larger than apreset number (process S205). The calculation data refers to dataregarding the parallel translations Δx and Δy and the rotation Δθ andthe position deviation at each position after the parallel translationsand the rotation are performed. For example, the preset number is set tobe equal to or larger than a value (e.g., 20) which allows adistribution of the calculation data to be a normal distribution.

If the cumulative number of the calculation data is less than the presetnumber (process S205: No), the cumulative number of the calculation datahas not reached a sufficient number for statistical analysis, and thereis a concern that the non-uniformity in the distribution of thecalculation data has been caused by an accidental disturbance. Thus, inthis case, the control device 70 returns to the process S201 and repeatsthe process S201 and the subsequent processes. That is, the processesS201 to S204 are repeated until the number of combined wafers T reachesa preset number.

Meanwhile, if the cumulative number of the calculation data is equal toor larger than the preset number (process S205: Yes), the cumulativenumber of the calculation data has reached the sufficient number for thestatistical analysis. Therefore, the control device 70 proceeds to aprocess S206 and performs the process S206 and subsequent processes.

In the process S206, by statistically analyzing the calculation data,the measurement data analyzer 701 sets correction data ΔX, ΔY and ΔΘ tobe used in the position adjustment in the horizontal direction betweenthe upper wafer W1 and the lower wafer W2 which is performed before thebonding is carried out. As the correction data ΔX, ΔY and ΔΘ, averagevalues of the calculation data Δx, Δy and Δθ may be used, for example.

Further, if the distribution of the calculation data does not become anormal distribution even if the cumulative number of the calculationdata has reached the preset number, median values of the calculationdata Δx, Δy and Δθ may be used as the correction data ΔX, ΔY and ΔΘ.

Then, the measurement data analyzer 701 predicts a position deviationwhen the position adjustment in the horizontal direction is performed byusing the correction data (process S207). For the purpose, the averagevalues (or the median values) of the calculation data may be used, forexample.

Then, the measurement data analyzer 701 sets a parameter which generatesa distortion of the lower wafer W2 to reduce the predicted positiondeviation (process S208). Besides (1) an attracting pressure on theattraction surface 141 a of the lower chuck 141 for attracting the lowerwafer W2, (2) a temperature of the lower wafer W2 or (3) a shape of theattraction surface 141 a of the lower chuck 141 may be used as theparameter which causes the distortion of the lower wafer W2.

(1) If a distribution of the attracting pressure on the attractionsurface 141 a of the lower chuck 141 is varied, a distribution of astress applied to the lower wafer W2 is changed, causing a shape of thelower wafer W2 to be changed. Thus, by controlling the distribution ofthe attracting pressure on the attraction surface 141 a of the lowerchuck 141, the distortion of the lower wafer W2 can be controlled. Theattraction surface 141 a of the lower chuck 141 is partitioned intomultiple regions, and the attracting pressure is set for each of themultiple regions individually. When the lower wafer W2 is attracted bythe attraction surface 141 a of the lower chuck 141, the attractingpressure may be generated in the entire attraction surface 141 a of thelower chuck 141, or only in a part of the attraction surface 141 a ofthe lower chuck 141. While maintaining the temperature of the lowerwafer W2 constant, it is possible to control the distortion of the lowerwafer W2.

(2) If the temperature distribution of the lower wafer W2 is changed,the shape of the lower wafer W2 is changed as the lower wafer W2 islocally contracted or expanded. Therefore, by controlling thetemperature distribution of the lower wafer W2, the distortion of thelower wafer W2 can be controlled. The control of the temperaturedistribution of the lower wafer W2 is carried out in the state that theattraction of the lower wafer W2 by the lower chuck 141 is released, forexample. Subsequently, the lower chuck 141 attracts the lower wafer W2in the state that there is generated non-uniformity in the temperaturedistribution of the lower wafer W2. Then, the shape of the lower waferW2 is fixed until the attraction of the lower wafer W2 is releasedagain. During a period until the attraction of the lower wafer W2 isreleased again, the shape of the lower wafer W2, which is made whenthere is the non-uniformity in the temperature distribution of the lowerwafer W2, is maintained even if the temperature distribution of thelower wafer W2 becomes uniform.

(3) If the shape of the attraction surface 141 a of the lower chuck 141is changed after the lower wafer W2 is attracted to the attractionsurface 141 a of the lower chuck 141, the shape of the lower wafer W2 ischanged to follow the change of the attraction surface 141 a. Thus, bycontrolling the shape of the attraction surface 141 a of the lower chuck141, the distortion of the lower wafer W2 can be controlled. Theattraction surface 141 a of the lower chuck 141 may be transformedbetween, for example, a flat surface and a curved surface. By way ofexample, the curved surface has an upwardly protruding dome shape. Ifthe attraction surface 141 a of the lower chuck 141 is transformed fromthe flat surface to the curved surface after the lower wafer W2 isattracted to the attraction surface 141 a of the lower chuck 141, thelower wafer W2 is also transformed to have the upwardly protruding domeshape. Accordingly, the lower wafer W2 can be expanded in a diametricaldirection, so that the size of the lower wafer W2 and the size of theupper wafer W1 can be made equal. The upper wafer W1 is bent to have adownwardly protruding dome shape by the striker 190 and thus expanded inthe diametrical direction.

The distortion of the lower wafer W2 may be controlled by controllingone of the above-described parameters (1) to (3), or by controlling aplurality of the parameters (1) to (3). When controlling the distortionof the lower wafer W2 by using the plurality of the parameters, acombination of the parameters is not particularly limited.

Furthermore, the correction data ΔX, ΔY and ΔΘ to be used in theposition adjustment in the horizontal direction between the upper waferW1 and the lower wafer W2 performed before the bonding is carried outmay be reset based on the setting of the parameter(s) which causes thedistortion of the lower wafer W2.

Through the above-described processes, the processing of deciding thesettings for use in the bonding apparatus 41 based on the measurementdata obtained by the alignment measuring device 55 is completed.

FIG. 14 is a flowchart illustrating an operation of the bondingapparatus based on the measurement data of the alignment measuringdevice according to the exemplary embodiment. Processes from a processS301 in FIG. 14 are performed under the control of the control device 70in response to an instruction for bonding the upper wafer W1 and thelower wafer W2 after the completion of the series of processes shown inFIG. 13 , for example.

First, the bonding system 1 bonds the upper wafer W1 and the lower waferW2 by performing the processes S101 to S114 of FIG. 8 according to thesettings obtained in the processes S206 and S208 of FIG. 13 (processS301).

By way of example, the distortion controller 703 performs the attractingand holding of the lower wafer W2 in the process S109 of FIG. 8 based onthe setting of the attracting pressure obtained in the process S208 ofFIG. 13 . Further, besides the attracting pressure, the distortion ofthe lower wafer W2 may be controlled by using the shape of theattraction surface, the temperature, or the like, as stated above.

Further, the position adjustment controller 702 performs the positionadjustment in the horizontal direction in the process S110 of FIG. 8based on the settings of the correction data ΔX, ΔY and ΔΘ obtained inthe process S206 of FIG. 13 . To elaborate, the position adjustmentcontroller 702 carries out the position adjustment in the horizontaldirection based on the image data obtained by the upper imaging unit151, the image data obtained by the lower imaging unit 161 and thecorrection data. A difference between a position of the lower chuck 141after the position adjustment in the horizontal direction based on bothimage data and the correction data and a position of the lower chuck 141after the position adjustment in the horizontal direction based on onlyboth image data is the same as, for example, the correction data.Furthermore, though the position adjustment in the horizontal directionis carried out by moving the lower chuck 141 in the present exemplaryembodiment, it can be achieved by moving the upper chuck 140 instead orby moving both the upper chuck 140 and the lower chuck 141, as mentionedabove.

Subsequently, the alignment measuring device 55 measures the relativeposition deviation between the upper wafer W1 and the lower wafer W2 atmultiple positions, the same as in the process S202 of FIG. 13 (processS302).

Then, the measurement data analyzer 701 calculates the paralleltranslations Δx and Δy and the rotation Δθ to minimize the size and thenon-uniformity of the position deviation therebetween, the same as inthe process S203 of FIG. 13 (process S303). Further, the measurementdata analyzer 701 calculates a position deviation at each position afterthe parallel translations and the rotation calculated in the processS303 are performed (process S304).

Further, the calculation of the parallel translations and the rotation(process S303) and the calculation of the position deviation at eachposition after the parallel translations and the rotation are performedare carried out substantially at the same time.

Afterwards, the determination unit 704 determines, through thestatistical analysis, whether there is the meaningful difference betweenthe position deviation generated in the previously performed bondingprocessing and the position deviation generated in the currentlyperformed bonding processing (process S305). It may be determinedthrough the statistical analysis whether there is a meaningfuldifference between a position deviation generated in the previouslyperformed bonding processings and a position deviation generated in themost recent bonding processings (including the current one). For thestatistical analysis, t-test (student's t-test) or F-test may be used,for example.

In this determination, the parallel translations Δx and Δy and therotation Δθ calculated in the process S203 of FIG. 13 and at least oneselected from the position deviation at the individual positionscalculated in the process S204 of FIG. 13 may be used as the positiondeviation generated in the previously performed bonding processing, forexample. Either Δx or Δy may be used.

Furthermore, in this determination, the parallel translations Δx and Δyand the rotation Δθ calculated in the process S303 of FIG. 14 and atleast one selected from the position deviation at the individualpositions calculated in the process S304 of FIG. 14 may be used as theposition deviation generated in the currently performed bondingprocessing, for example. Either Δx or Δy may be used.

If there is the meaningful difference between the position deviationgenerated in the previously performed bonding processing and theposition deviation generated in the currently performed bondingprocessing (process S305; Yes), a quality of the combined wafer T mayfall out of a tolerance range, and there is a likelihood that a problemsuch as an attraction failure may be generated. Thus, in such a case,the determination unit 704 makes a determination that there isabnormality (process S306), and the current processing is ended.

Further, if the determination unit 704 makes the determination of theabnormality, the control device 70 may notify an alarm to a user of thebonding system 1. The alarm is outputted in the form of an image, asound or a buzzer. After the user repairs the bonding system 1, theprocessing from the process S301 is resumed. As stated, by stopping thebonding processing when there is a problem such as the attractionfailure, production of defective products, which is a waste, can besuppressed.

Meanwhile, if there is no meaningful difference between the positiondeviation generated in the previously performed bonding processing andthe position deviation generated in the currently performed bondingprocessing (process S305; No), the quality of the combined wafer T fallswithin the tolerance range. In such a case, the determination unit 704makes a determination of normality (process S307), and the currentprocessing is ended.

As stated above, according to the present exemplary embodiment, theposition adjustment in the horizontal direction in the currentlyperformed bonding processing is controlled based on the positiondeviation between the alignment marks generated in the previouslyperformed bonding processing. Thus, the position deviation between thealignment marks, which is not solved in the position adjustment in thehorizontal direction performed based on only the image data of the upperimaging unit 151 or the lower imaging unit 161, can be reduced.

Moreover, according to the present exemplary embodiment, the distortionof the lower wafer W2 in the currently performed bonding processing iscontrolled based on the position deviation between the alignment marksgenerated in the previously performed bonding processing. Accordingly,the position deviation between the alignment marks, which is not solvedin the relative parallel translations or rotation between the upperwafer W1 and the lower wafer W2, can be reduced.

In addition, according to the present exemplary embodiment, it isdetermined through the statistical analysis whether there is themeaningful difference between the position deviation between thealignment marks generated in the previously performed bonding processingand the position deviation between the alignment marks generated in thecurrently performed bonding processing. Accordingly, it is possible todetermine whether the quality of the combined wafer T falls out of thetolerance range, and it can be determined whether a problem such as theattraction failure has occurred. In case that the problem such as theattraction failure is generated, by stopping the bonding processing, theproduction of defective products, which is a waste, can be suppressed.

<Control Over Distortion of Lower Wafer>

FIG. 15 is a diagram illustrating the attraction surface of the lowerchuck according to the exemplary embodiment. The lower chuck 141 shownin FIG. 15 has, on the attraction surface 141 a configured to attractthe lower wafer W2, multiple regions (for example, circular arc regionsA1, circular arc regions A2, circular arc regions B1, circular arcregions B2 and a circular region C) in which the attracting pressure(for example, a vacuum pressure) for attracting the lower wafer W2 iscontrolled independently. The circular arc regions A1 and A2 arearranged alternately in a circumferential direction, forming a ringregion A. Inside this ring region A in a diametrical direction, thecircular arc regions B1 and B2 are arranged alternately in thecircumferential direction, forming a ring region B. Inside this ringregion B, the circular region C is formed. That is, the attractionsurface 141 a is divided into the ring region A, the ring region B andthe circular region C as it goes inwards in the diametrical direction.The ring region A is divided into multiple circular arc regions A1 andA2 in the circumferential direction. Likewise, the ring region B isdivided into multiple circular arc regions B1 and B2 in thecircumferential direction.

One vacuum pump 251 is connected to the multiple circular arc regions A1via pipelines which are equipped with one electro-pneumatic regulator261 (in FIG. 15 , only a pipeline connected to the single circular arcregion A1 is illustrated). Likewise, one vacuum pump 252 is connected tothe multiple circular arc regions A2 via pipelines which are equippedwith one electro-pneumatic regulator 262 (in FIG. 15 , only a pipelineconnected to the single circular arc region A2 is illustrated). Further,one vacuum pump 253 is connected to the multiple circular arc regions B1via pipelines which are equipped with one electro-pneumatic regulator263 (in FIG. 15 , only a pipeline connected to the single circular arcregion B1 is illustrated). Likewise, one vacuum pump 254 is connected tothe multiple arc regions B2 via pipelines which are equipped with oneelectro-pneumatic regulator 264 (in FIG. 15 , only a pipeline connectedto the single circular arc region B2 is illustrated). Furthermore, onevacuum pump 255 is connected to the single circular region C via apipeline which is equipped with one electro-pneumatic regulator 265.

If the control device 70 operates the vacuum pump 251, the vacuum pump251 generates the vacuum pressure in each of the circular arc regionsA1. This vacuum pressure is maintained at a predetermined set value bythe electro-pneumatic regulator 261, so that an attracting pressurecorresponding to this set value is generated in each of the circular arcregions A1. If the control device 70 stops the operation of the vacuumpump 251, each circular arc region A1 is turned back into an atmosphericpressure, so that the generation of the attracting pressure in eachcircular arc region A1 is stopped. Since the generation and the releaseof the attracting pressure in the other circular arc regions A2, B1 andB2 and in the circular region C are the same as the generation and therelease of the attracting pressure in the circular arc regions A1,redundant description thereof will be omitted here.

The vacuum pumps 251 to 255, the electro-pneumatic regulators 261 to265, and so forth constitute an attracting pressure distributionadjuster 250. The attracting pressure distribution adjuster 250 isconfigured to adjust a distribution of the attracting pressure of thelower chuck 141 configured to attract the lower wafer W2, thusgenerating the distortion of the lower wafer W2. The distribution of theattracting pressure can be varied by selecting operating target vacuumpumps from the vacuum pumps 251 to 255 or by changing the set values forthe electro-pneumatic regulators 261 to 265. This changing of thesettings is performed by the distortion controller 703. Further, thelayout of the regions in which the attracting pressures are controlledindependently is not limited to the example shown in FIG. 15 .

Further, though the lower chuck 141 is configured to vacuum-attract thelower wafer W2 in the present exemplary embodiment, the lower chuck 141may be configured to attract the lower wafer W2 electrostatically. Inthis case, the attracting pressure distribution adjuster 250 includesmultiple internal electrodes embedded in the lower chuck 141; a powersupply configured to supply a power to the internal electrodes; and soforth. The power supply may be a step-down DC/DC converter, a step-upDC/DC converter, or the like. The distribution of the attractingpressure can be varied by altering, among the multiple internalelectrodes, the internal electrode which supplies the power, by changingthe power to be fed, and so forth.

FIG. 16 is a side view illustrating the upper chuck, the lower chuck anda temperature distribution adjuster according to the exemplaryembodiment. The upper chuck 140 and a temperature distribution adjuster500 are fixed to a common horizontal frame 590, and the lower chuck 141is disposed below the upper chuck 140 and the temperature distributionadjuster 500.

The temperature distribution adjuster 500 causes the distortion of thelower wafer W2 by adjusting the temperature distribution of the lowerwafer W2 held by the lower chuck 141. The temperature distributionadjuster 500 includes a main body 510 having a bottom surface of adiameter larger than a diameter of the lower wafer W2; a supportingmember 520 configured to support the main body 510 from above it; and anelevating unit 530 configured to move the supporting member 520 in thevertical direction.

The main body 510 is configured to be movable up and down under thehorizontal frame 590. The elevating unit 530 is fixed to the horizontalframe 590 and configured to move the main body 510 up and down withrespect to the horizontal frame 590. Accordingly, a distance between themain body 510 and the lower chuck 141 can be adjusted.

FIG. 17 is a side cross sectional view illustrating the main body of thetemperature distribution adjuster according to the exemplary embodiment.The main body 510 includes, as depicted in FIG. 17 , a cooling unit 550and a heating unit 560.

The cooling unit 550 is, for example, a flow path formed within the mainbody 510 and is connected to an inlet line 551 through which a coolantsuch as cooling water is introduced into the cooling unit 550 and anoutlet line 552 through which the coolant is flown out from the coolingunit 550. By circulating the temperature-controlled coolant in thiscooling unit 550, the entire surface of the lower wafer W2 can be cooledin a uniform manner.

Meanwhile, the heating unit 560 is configured to heat the lower wafer W2locally. To elaborate, the heating unit 560 includes multipleindependent heating regions 561 a, and by heating these heating regions561 a selectively, a part of or the entire of the lower wafer W2 can beheated. The selection of the heating regions 561 a is carried out by thedistortion controller 703.

According to the present exemplary embodiment, the local heating of thelower wafer W2 by the heating unit 560 and the temperature adjustment ofthe lower wafer W2 by the cooling unit 550 can be performed at the sametime. Further, though the local heating of the lower wafer W2 isperformed in the present exemplary embodiment, the local cooling of thelower wafer W2 may be performed. Any of various heating or coolingmethods can be adopted as long as the non-uniform temperaturedistribution of the lower wafer W2 can be created.

By way of example, the adjustment of the temperature distribution of thelower wafer W2 is performed in the state that the attraction of thelower wafer W2 by the lower chuck 141 is released. Then, in the statethat there is created the non-uniformity in the temperature distributionof the lower wafer W2, the lower wafer W2 is attracted by the lowerchuck 141. Thereafter, the bonding between the lower wafer W2 and theupper wafer W1 is performed, and the shape of the lower wafer W2 isfixed until the attraction of the lower wafer W2 is released again.

FIG. 18A and FIG. 18B are side cross sectional views illustrating alower chuck according to a modification example. FIG. 18A illustrates astate when an attraction surface 141 a of a lower chuck 141 is a flatsurface, and FIG. 18B illustrates a state when the attraction surface141 a of the lower chuck 141 is an upwardly protruding dome-shapedcurved surface. The lower chuck 141 according to the presentmodification example includes an elastic transformation member 610having the attraction surface 141 a configured to attract the lowerwafer W2; and a base member 620 configured to support the elastictransformation member 610.

The elastic transformation member 610 has suction grooves 601 on theattraction surface 141 a which attracts the lower wafer W2. A layout ofthe suction grooves 601 may be selected as required. The suction grooves601 are connected to a vacuum pump 603 via suction lines 602. If thevacuum pump 603 is operated, the lower wafer W2 is vacuum-attracted to atop surface of the elastic transformation member 610. Meanwhile, if theoperation of the vacuum pump 603 is stopped, the vacuum-attraction ofthe lower wafer W2 is released.

The elastic transformation member 610 is formed of alumina ceramic or aceramic material such as, but not limited to, SiC. Further, the basemember 620 is also formed of alumina ceramic or a ceramic material suchas, but not limited to, SiC, the same as the elastic transformationmember 610.

The base member 620 is disposed under the elastic transformation member610, and a fixing ring 630 is provided around the elastic transformationmember 610. A peripheral portion of the elastic transformation member610 is fixed to the base member 620 by the fixing ring 630.

A sealed pressure-variable space 640 is formed between a bottom surfaceof the elastic transformation member 610 and a top surface of the basemember 620. An attraction surface transforming unit 650 is configured toadjust a shape of the attraction surface 141 a of the elastictransformation member 610 by adjusting an air pressure within thepressure-variable space 640.

The attraction surface transforming unit 650 has an air feed/exhaustline 651, and the air feed/exhaust line 651 is connected to an airfeed/exhaust opening 621 formed at a top surface of the base member 620.An electro-pneumatic regulator 653 configured to supply air into thepressure-variable space 640 and a vacuum pump 654 configured to exhaustthe air from the pressure-variable space 640 are connected to the airfeed/exhaust line 651 via a switching valve 652. The switching valve 652is switched into between a state (A) and a state (B): (A) a flow pathconnecting the switching valve 652 and the vacuum pump 654 is opened forthe air feed/exhaust opening 621, and a flow path connecting theswitching valve 652 and the electro-pneumatic regulator 653 is closedfor the air feed/exhaust opening 621; and (B) the flow path connectingthe switching valve 652 and the vacuum pump 654 is closed for the airfeed/exhaust opening 621, and the flow path connecting the switchingvalve 652 and the electro-pneumatic regulator 653 is opened for the airfeed/exhaust opening 621.

As depicted in FIG. 18A, if the inside of the pressure-variable space640 is decompressed (for example, −10 kPa) by being evacuated throughthe vacuum pump 654, the elastic transformation member 610 is attractedto the base member 620. In this state, the top surface of the elastictransformation member 610 becomes the flat surface.

Meanwhile, as shown in FIG. 18B, if the inside of the pressure-variablespace 640 is pressurized (for example, 0 kPa to 100 kPa) by supplyingthe air thereinto through the electro-pneumatic regulator 653, theelastic transformation member 610 is pressed from below it. Since theperipheral portion of the elastic transformation member 610 is fixed tothe base member 620 by the fixing ring 630, a central portion of theelastic transformation member 610 is protruded higher than theperipheral portion thereof, and the top surface of the elastictransformation member 610 becomes the curved surface. This curvedsurface is of an upwardly protruding dome shape. A radius of curvatureof this curved surface can be controlled by adjusting the air pressurewithin the pressure-variable space 640. Changing of the setting of theair pressure within the pressure-variable space 640 is carried out bythe distortion controller 703.

If the shape of the attraction surface 141 a of the lower chuck 141 ischanged after the lower wafer W2 is attracted to the attraction surface141 a of the lower chuck 141, the shape of the lower wafer W2 is changedto conform to the attraction surface 141 a. Thus, by changing the shapeof the attraction surface 141 a of the lower chuck 141, the distortionof the lower wafer W2 can be controlled.

<Modifications and Improvements>

So far, the exemplary embodiment of the bonding system and the bondingmethod have been described. However, the present disclosure is notlimited to the above-described exemplary embodiment or the like. Variouschanges, corrections, replacements, addition, deletion and combinationsmay be made within the scope of the claims, and all of these areincluded in the scope of the inventive concept of the presentdisclosure.

In the above-described exemplary embodiment and modification example,the attracting pressure distribution adjuster 250, the temperaturedistribution adjuster 500 or the attracting surface transforming unit650 is used as a distortion generator. Under the control of thedistortion controller 703, the distortion generator is configured togenerate the distortion of the lower wafer W2 attracted to the lowerchuck 141. The attracting pressure distribution adjuster 250, thetemperature distribution adjuster 500 and the attraction surfacetransforming unit 650 may be used individually or in combinations. Here,the combinations are not particularly limited.

The distortion controller 703 according to the above-described exemplaryembodiment and modification example controls the distortion of the lowerwafer W2 attracted to the lower chuck 141. However, the distortioncontroller 703 may control the distortion of the upper wafer W1attracted to the upper chuck 140. That is, though the upper wafer W1,the upper chuck 140, the lower wafer W2 and the lower chuck 141correspond to the first substrate, the first holder, the secondsubstrate and the second holder, respectively, in the above-describedexemplary embodiment and modified example, the upper wafer W1, the upperchuck 140, the lower wafer W2 and the lower cuck 141 may correspond tothe second substrate, the second holder, the first substrate and thefirst holder, respectively. Furthermore, the distortion controller 703may control both the distortion of the lower wafer W2 and the distortionof the upper wafer W1.

This application claims the benefit of Japanese Patent Application No.2018-008892 filed on Jan. 23, 2018, the entire disclosures of which areincorporated herein by reference.

According to the exemplary embodiments, it is possible to improveaccuracy of position adjustment between a substrate at an upper side anda substrate at a lower side in the horizontal direction, which isperformed before bonding of the two substrates is carried out.

The claims of the present application are different and possibly, atleast in some aspects, broader in scope than the claims pursued in theparent application. To the extent any prior amendments orcharacterizations of the scope of any claim or cited document madeduring prosecution of the parent could be construed as a disclaimer ofany subject matter supported by the present disclosure, Applicantshereby rescind and retract such disclaimer. Accordingly, the referencespreviously presented in the parent applications may need to berevisited.

We claim:
 1. A bonding system, comprising: a first holder and a secondholder arranged to be spaced apart from each other in a verticaldirection, the first holder having, on a surface thereof facing thesecond holder, an attraction surface configured to attract and hold afirst substrate, and the second holder having, on a surface thereoffacing the first holder, an attraction surface configured to attract andhold a second substrate; a position adjuster configured to move thefirst holder and the second holder relatively to perform a positionadjustment in a horizontal direction between the first substrate held bythe first holder and the second substrate held by the second holder; apressing unit configured to press the first substrate held by the firstholder and the second substrate held by the second holder against eachother; a position adjustment controller configured to receive, after thefirst substrate and the second substrate are pressed against each otherby the pressing unit and a bonding of the first substrate and the secondsubstrate is completed, measurement data obtained by measuring aposition deviation between an alignment mark formed on the firstsubstrate and an alignment mark formed on the second substrate in astate upon the completion of the bonding from a measuring unitpositioned outside the bonding system, and configured to control theposition adjustment in the horizontal direction in a currently-performedbonding processing based on the position deviation generated in apreviously-performed bonding processing; a distortion generatorconfigured to generate a distortion of the second substrate held by thesecond holder; and a distortion controller configured to control thedistortion in the currently-performed bonding processing based on theposition deviation generated in the previously-performed bondingprocessing.
 2. The bonding system of claim 1, wherein the distortiongenerator comprises an attracting pressure distribution adjusterconfigured to generate the distortion of the second substrate byadjusting a distribution of an attracting pressure of the second holderconfigured to attract the second substrate.
 3. The bonding system ofclaim 2, wherein the distortion generator comprises a temperaturedistribution adjuster configured to generate the distortion of thesecond substrate by adjusting a temperature distribution of the secondsubstrate.
 4. The bonding system of claim 3, wherein the distortiongenerator comprises an attraction surface transforming unit configuredto generate, by transforming the attraction surface of the second holderconfigured to attract the second substrate, the distortion of the secondsubstrate previously attracted to the attraction surface.
 5. The bondingsystem of claim 4, further comprising: a determination unit configuredto determine, through a statistical analysis, whether there is ameaningful difference between the position deviation generated in thepreviously-performed bonding processing and the position deviationgenerated in the currently-performed bonding processing.
 6. A bondingsystem, comprising: a first holder and a second holder arranged to bespaced apart from each other in a vertical direction, the first holderhaving, on a surface thereof facing the second holder, an attractionsurface configured to attract and hold a first substrate, and the secondholder having, on a surface thereof facing the first holder, anattraction surface configured to attract and hold a second substrate; aposition adjuster configured to move the first holder and the secondholder relatively to perform a position adjustment in a horizontaldirection between the first substrate held by the first holder and thesecond substrate held by the second holder; a pressing unit configuredto press the first substrate held by the first holder and the secondsubstrate held by the second holder against each other; a positionadjustment controller configured to receive, after the first substrateand the second substrate are pressed against each other by the pressingunit and a bonding of the first substrate and the second substrate iscompleted, measurement data obtained by measuring a position deviationbetween an alignment mark formed on the first substrate and an alignmentmark formed on the second substrate in a state upon the completion ofthe bonding from a measuring unit positioned outside the bonding system,and configured to control the position adjustment in the horizontaldirection in a currently-performed bonding processing based on theposition deviation generated in a previously-performed bondingprocessing; a determination unit configured to determine, through astatistical analysis, whether there is a meaningful difference betweenthe position deviation generated in the previously-performed bondingprocessing and the position deviation generated in thecurrently-performed bonding processing.
 7. The bonding system of claim1, wherein if a cumulative number of a calculation data of the positiondeviation generated in the previously-performed bonding processing isequal to or larger than a preset number, the position adjustmentcontroller is configured to control the position adjustment in thehorizontal direction in the currently-performed bonding processing basedon the cumulated calculation data, and if the cumulative number is lessthan the preset number, the position adjustment controller is configurednot to control the position adjustment in the horizontal direction inthe currently-performed bonding processing based on the cumulatedcalculation data.
 8. The bonding system of claim 1, wherein thedistortion generator comprises a temperature distribution adjusterconfigured to generate the distortion of the second substrate byadjusting a temperature distribution of the second substrate.
 9. Thebonding system of claim 1, wherein the distortion generator comprises anattraction surface transforming unit configured to generate, bytransforming the attraction surface of the second holder configured toattract the second substrate, the distortion of the second substratepreviously attracted to the attraction surface.
 10. The bonding systemof claim 2, wherein the distortion generator comprises an attractionsurface transforming unit configured to generate, by transforming theattraction surface of the second holder configured to attract the secondsubstrate, the distortion of the second substrate previously attractedto the attraction surface.
 11. The bonding system of claim 8, whereinthe distortion generator comprises an attraction surface transformingunit configured to generate, by transforming the attraction surface ofthe second holder configured to attract the second substrate, thedistortion of the second substrate previously attracted to theattraction surface.
 12. The bonding system of claim 1, furthercomprising: a determination unit configured to determine, through astatistical analysis, whether there is a meaningful difference betweenthe position deviation generated in the previously-performed bondingprocessing and the position deviation generated in thecurrently-performed bonding processing.
 13. The bonding system of claim2, further comprising: a determination unit configured to determine,through a statistical analysis, whether there is a meaningful differencebetween the position deviation generated in the previously-performedbonding processing and the position deviation generated in thecurrently-performed bonding processing.
 14. The bonding system of claim3, further comprising: a determination unit configured to determine,through a statistical analysis, whether there is a meaningful differencebetween the position deviation generated in the previously-performedbonding processing and the position deviation generated in thecurrently-performed bonding processing.
 15. The bonding system of claim8, further comprising: a determination unit configured to determine,through a statistical analysis, whether there is a meaningful differencebetween the position deviation generated in the previously-performedbonding processing and the position deviation generated in thecurrently-performed bonding processing.
 16. The bonding system of claim9, further comprising: a determination unit configured to determine,through a statistical analysis, whether there is a meaningful differencebetween the position deviation generated in the previously-performedbonding processing and the position deviation generated in thecurrently-performed bonding processing.
 17. The bonding system of claim2, wherein if a cumulative number of a calculation data of the positiondeviation generated in the previously-performed bonding processing isequal to or larger than a preset number, the position adjustmentcontroller is configured to control the position adjustment in thehorizontal direction in the currently-performed bonding processing basedon the cumulated calculation data, and if the cumulative number is lessthan the preset number, the position adjustment controller is configurednot to control the position adjustment in the horizontal direction inthe currently-performed bonding processing based on the cumulatedcalculation data.
 18. The bonding system of claim 6, wherein if acumulative number of a calculation data of the position deviationgenerated in the previously-performed bonding processing is equal to orlarger than a preset number, the position adjustment controller isconfigured to control the position adjustment in the horizontaldirection in the currently-performed bonding processing based on thecumulated calculation data, and if the cumulative number is less thanthe preset number, the position adjustment controller is configured notto control the position adjustment in the horizontal direction in thecurrently-performed bonding processing based on the cumulatedcalculation data.
 19. The bonding system of claim 8, wherein if acumulative number of a calculation data of the position deviationgenerated in the previously-performed bonding processing is equal to orlarger than a preset number, the position adjustment controller isconfigured to control the position adjustment in the horizontaldirection in the currently-performed bonding processing based on thecumulated calculation data, and if the cumulative number is less thanthe preset number, the position adjustment controller is configured notto control the position adjustment in the horizontal direction in thecurrently-performed bonding processing based on the cumulatedcalculation data.
 20. The bonding system of claim 9, wherein if acumulative number of a calculation data of the position deviationgenerated in the previously-performed bonding processing is equal to orlarger than a preset number, the position adjustment controller isconfigured to control the position adjustment in the horizontaldirection in the currently-performed bonding processing based on thecumulated calculation data, and if the cumulative number is less thanthe preset number, the position adjustment controller is configured notto control the position adjustment in the horizontal direction in thecurrently-performed bonding processing based on the cumulatedcalculation data.